Magnetic card reader

ABSTRACT

This invention aims to provide a magnetic head for a magnetic reader improved so that the data can be read out from the magnetic storage medium with high security, that is, without an anxiety that the data might be illegally read out and, even if the data is illegally read out, such illegally read out data can not be used by the illegal person. 
     Here is disclosed a magnetic head of a magnetic card reader adapted to read out data stored on a magnetic card, comprising a core with a coil for sensing of the data stored on the card as analog signals, an A/D converter chip adapted to convert the analog signals to corresponding digital signals and a microprocessor adapted to encrypt the digital signals. The A/D converter chip and the microprocessor (IC) are fixed within a housing by means of a synthetic resin.

BACKGROUND OF THE INVENTION

This invention relates to a magnetic head used in a magnetic reader.

A magnetic head of a magnetic reader adapted to read out data stored ona magnetic storage medium is well known. An example of a conventionalmagnetic head as is used for a magnetic card reader 70 will be describedhereunder in reference to FIG. 7. The magnetic card reader 70 reads datafrom a magnetic stripe of the magnetic card 71 through a magnetic head72 coming in contact with a surface of the magnetic card 71 passingthrough a guide groove (not shown) of the magnetic card reader 70. Themagnetic card reader 70 comprises the magnetic head 72, an A/D converter74 connected to the magnetic head 72 via an interface cable 73 and acontrol unit 76 connected to the A/D converter 74 via an interface cable75.

The magnetic head 72 has a core and a coil wound around the core. Thecontrol unit 76 is a computer having a CPU, a memory, a hard disc, aCD-ROM drive and a floppy disc drive. Though not shown, a display(display device), a keyboard (input device) and a printer (outputdevice) are connected to the control unit 76 via interface cables.

As the magnetic card 71 with the magnetic stripe passes through theguide groove of the magnetic card reader 70 by the distal end (core gap)of the magnetic head 72, a magnetic flux changes around the core andthereby an induced electromotive force is generated so that an electriccurrent flows in the coil to cancel a variation of the magnetic flux.The current flows from the coil to the A/D converter 74 via theinterface cable 73 and is detected by the A/D converter as analogsignals. The A/D converter 74 converts the analog signals input from themagnetic head 72 to corresponding digital signals. The digital signalsare output from the A/D converter 74 to the control unit 76 via theinterface cable 75. The control unit 76 amplifies the digital signalsand outputs the digital signals via the display and/or the printer inthe form of character data and/or print data, respectively. Furthermore,the control unit 76 stores the data in the form of digital signals inits memory.

The magnetic card reader is generally classified into the reader ofmanual slide type in which the magnetic card is manually moved along aguide groove and the reader of electric motor-driven insertion type inwhich the magnetic card inserted into a card inlet is moved by a drivingbelt or a driving roller.

With the magnetic card reader 70 shown in FIG. 7, if any devices areconnected to the interface cables 73, 75, it is possible that the analogsignals through the magnetic head 72 might be illegally read out via thecable 73 or the digital signals converted by the A/D converter 74 mightbe read out via the cable 75. It is also possible that the data storedin the memory might be illegally read out via the cables 73, 75. Bothwriting and reading data in and from the magnetic card are relativelyeasy in view of the method of recording on the magnetic card.Accordingly, the magnetic card would be easily duplicated using the datain the form of analog or digital signals which is illegally read out.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a magnetic head for amagnetic reader improved so as to make it difficult for others to readout data illegally in the process of reading data from a magneticstorage medium and so as to encrypt the data in order to make the dataunavailable to others even if the data is illegally read out.

According to this invention, there is provided a magnetic head of amagnetic reader adapted to read data from a magnetic storage medium.

The magnetic head comprises a core with a coil adapted to sense the datastored on the storage medium in the form of analog signals, an A/Dconverter chip electrically connected to the coil and adapted to convertthe analog signals to corresponding digital signals and an ICelectrically connected to the A/D converter chip and adapted to encryptthe digital signals.

This invention includes the following embodiments. The magnetic headfurther comprises a housing defining an outer peripheral surface of themagnetic head and containing therein the core, the A/D converter chipand the IC.

The A/D converter chip and the IC are fixed within the housing by meansof a synthetic resin.

The magnetic reader includes a node terminal adapted to decrypt thedigital signals having been encrypted by the IC and electricallyconnected to the IC of the magnetic head.

The IC is selected from a group including a microprocessor, a gatearray, a field programmable gate array and a dedicated hard ware.

The magnetic storage medium is a magnetic card and the magnetic readeris a magnetic card reader.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematically illustrating a magnetic cardreader;

FIG. 2 is a diagram schematically illustrating an internal constructionof a card reading station;

FIG. 3 is a partially cutaway perspective view showing a magnetic headincorporated in the card reading station;

FIG. 4 is a flow chart illustrating a sequence of encryption anddecryption effectuated between a microprocessor and a data controlstation;

FIG. 5 is a block diagram schematically illustrating an alternativeembodiment of the magnetic card reader;

FIG. 6 is a flow chart illustrating a sequence of encryption anddecryption effectuated between the microprocessor and a host computer;and

FIG. 7 is a diagram schematically illustrating a well-known magnetichead used in the magnetic card reader.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Details of a magnetic head used in a magnetic reader according to thisinvention will be more fully understood from the description of amagnetic head used in a magnetic card reader given hereunder inreference to the accompanying drawings.

FIG. 1 is a block diagram schematically illustrating a magnetic cardreader 1, FIG. 2 is a diagram schematically illustrating an internalstructure of a card reading station 2 and FIG. 3 is a partially cutawayperspective view showing a magnetic head 17 incorporated in the cardreading station 2. In FIG. 3, a core 19 of the magnetic head 17 has itsdistal end 19 a in contact with an upper surface of a magnetic card 23.FIG. 3 shows the interior of a housing 18 by partially cutting asynthetic resin 22 filled in the housing 18.

As will be apparent from FIG. 1, the magnetic card reader 1 comprisesthe card reading station 2 adapted to sense data stored on a magnetizedlayer 26 of the magnetic card 23 in the form of electric signals and adata control station 4 (terminal node) connected to the card readingstation 2 via an interface cable 3. The data control station 4 is acomputer comprising a CPU (central processing unit), a memory (auxiliarymemory), a hard disc, a CD-ROM drive and a floppy disc drive. A display5 (display device) adapted to output data in the form of characterinformation, a keyboard 6 (input device) adapted to add and/or changedata and a printer 6 (output device) adapted to output the data in theform of printed information are connected to the data control station 4via interface cables 7, 8.

As will be seen in FIG. 2, the card reading station 2 is of motor-driveninsertion type and has a card inlet 9 on its front end, a card outlet 10on its rear end and a card guiding rail 11 extending from the card inlet9 to the card outlet 10. The card reading station 2 is provided at itslongitudinally middle region with the magnetic head 17 which will behereinafter described more in detail. In the vicinity of the inlet 9,the outlet 10 and the magnetic head 17, there are provided photo-sensors12, 13, 14, respectively, for position-detection of the magnetic card 23moving along the guiding rail 11. Upon insertion of the magnetic card 23into the inlet 9 of the card reading station 2, the magnetic card 23 isautomatically moved along the guiding rail 11 and is ejected from theoutlet 10.

In the card reading station 2, the distal end 19 a of the core 19 (SeeFIG. 3) constituting the magnetic head 17 is opposed to the guiding rail11. The card 23 is moved along the guiding rail 11 on a belt 15 providedwithin the card reading station 2. The belt 15 is driven by motor 16rotates.

As will be seen in FIG. 3, the magnetic head 17 comprises the housing 18covering an outer peripheral surface thereof, the core 19 provided withcoil (not shown), an A/D converter chip 20 electrically connected to thecoil and a microprocessor 21 (IC) electrically connected to the A/Dconverter chip 20. In the magnetic head 17, the core 19, the A/Dconverter chip 20 and the microprocessor 21 are contained within thehousing 18. In the magnetic head 17, the distal end 19 a of the core 19is exposed outward from the lower end of the housing 18. Though notshown, the microprocessor 21 includes an arithmetic unit, a control unitand a cache memory.

The A/D converter chip 20 and the microprocessor 21 are entirely fixedto the inside of the housing 18 by means of synthetic resin 22 filled inthe housing 18. As the synthetic resin 22, it is preferred to use asuitable thermosetting synthetic resin. It is also possible to use athermoplastic synthetic resin in the place of the thermosettingsynthetic resin.

The magnetic card 23 is composed of a color print layer 24, a base layer25, a magnetized layer 26, a shield layer 27 and a print layer 28 whichare overlaid in this order from the lower surface of the magnetic card23. In the magnetic card 23, the magnetized layer 26 is made from aferromagnetic material and the base layer 25 is made from a polyethyleneterephthalate.

When the magnetic card 23 is inserted through the card inlet 9 into thecard reading station 2, the photo-sensor 12 detects the magnetic card 23and outputs a card insertion signal to the data control station 4. Uponreceipt of the card insertion signal, the data control station 4 outputsa command to the microprocessor 21 of the magnetic head 17 for readingof the data stored on this card 23.

When the magnetized layer 26 of the magnetic card 23 passes by thedistal end 19 a of the core 19 (i.e., core gap) constituting themagnetic head 17, a magnetic flux changes around the core 19 whereuponan induced electromotive force is generated and an electric currentflows in the coil. A value of the electric current flowing in the coilis dependent on the variation of the magnetic flux and input to the A/Dconverter chip 20 in the form of analog signals. The A/D converter tip20 converts the analog signals to the corresponding digital signals. Thedigital signals are then input to the microprocessor 21 connected to theA/D converter chip 20. The microprocessor 21 encrypts the digitalsignals. The encrypted digital signals are then output from themicroprocessor 21 to the data control station 4.

If the photo-sensors 13, 14 detect the magnetic card 23 passing by themagnetic head 17 and then being ejected from the card outlet 10, thephoto-sensors 13, 14 respectively output card passage signals to thedata control station 4. In response to the card passage signals, thedata control station 4 commands the microprocessor 21 to stop readingdata.

The data control station 4 has an amplifier (not shown) foramplification of the digital signals and decrypts the digital signalshaving been amplified by the amplifier. The data control station 4 mayoutput the decrypted digital signals to the display 5 or the printer 6.The data control station 4 stores the encrypted or decrypted digitalsignals in the memory. The data control station 4 includes a cachememory so that the encrypted or decrypted digital signals may be storedalso in the cache memory.

FIG. 4 is a flow chart illustrating a sequence of encryption anddecryption effectuated between the data control station 4 and themicroprocessor 21. In the magnetic card reader 1 according to thisinvention, the public key cryptosystem (RSA pubic key cryptosystem) isadopted to encrypt and decrypt the data between the data control station4 and the microprocessor 21.

Upon receipt of the card insertion signal from the photo-sensor 12, thedata control station 4 generates a public key 30 for the encryption ofthe data stored on the magnetic card 23 and a private key 31 for thedecryption of the data having been encrypted in this manner.

The private key 31 is input to a key management utility 32 of the CPU,in which the private key 31 is address-allocated in a predeterminedmanner. The private key 31 is then input from the key management utility32 to a private key file 33 of the memory and stored therein. The publickey 30, on the other hand, is input from the data control station 4 to akey management utility 34 of the microprocessor 21 via the interfacecable 3 and is address-allocated in a predetermined manner in the keymanagement utility 34. The public key 30 is input from the keymanagement utility 34 to the cache memory of the microprocessor 21 andstored in a public key file 35 of the cache memory.

Upon receipt of digital signals 36 from the A/D converter chip 20, themicroprocessor 21 takes the public key 30 out from the public key file35 and makes up a RSA algorithm 37 using the public key 30. Themicroprocessor 21 encrypts the digital signals 36 in accordance with theRSA algorithm 37 and outputs the encrypted digital signals 36 to thedata control station 4 via the interface cable 3. Upon receipt of theencrypted digital signals 36 from the microprocessor 21, the datacontrol station 4 takes the private key 31 out from the private key file33 of the memory and makes up a RSA algorithm 38 using the private key31. The private key 31 taken out from the private key file 33corresponds to the public key 30 which has been used by themicroprocessor 21 to encrypt the digital signals 36. The data controlstation 4 decrypts the encrypted digital signals 36 in accordance withthe RSA algorithm 38 and thereby obtains data 39 stored on the magneticcard 23.

In the magnetic card reader 1 according to this invention, both the A/Dconverter chip 20 and the microprocessor 21 are contained within thehousing 18 and therefore it is impossible to attach a device adapted forillegal reading of the data in the form of the analog or digital signalsto the magnetic card reader 1 without disassembly of the magnetic head17. Consequently, it is difficult to read out the data illegally. In themagnetic card reader 1, the magnetic head 17 includes the microprocessor21 adapted to encrypt the data stored on the magnetic card 23.Consequently, even if the data stored on the magnetic card 23 isillegally read out, the data can not be used without decrypting theencrypted data. It is thus practically impossible to duplicate themagnetic card 23.

FIG. 5 is a block diagram schematically illustrating an alternativeembodiment 40 of the magnetic card reader and FIG. 6 is a flow chartillustrating a sequence of encryption and decryption effectuated betweenthe microprocessor 21 and a host computer 43.

The magnetic card reader 40 includes a card reading station 41. The cardreading station 41 contains therein the same magnetic head 17 as thatshown in FIG. 3 adapted to convert the data stored on the magnetic card23 to the corresponding digital signals and to encrypt the digitalsignals. The card reading station 41 of the magnetic card reader 40 hasthe same structure as that shown in FIG. 2 and detailed descriptionthereof will be eliminated here. The magnetic card reader 40 isexternally connected to the host computer 43 (node terminal) via aninterface cable 42.

The magnetic head 17 mounted on the card reading station 41 comprisesthe housing 18, the core 19 with the coil, the A/D converter chip 20 andthe microprocessor 21 (MPU). In the magnetic head 17, the core 19 andthe A/D converter chip 20 are contained within the housing 18 whereinthe A/D converter chip 20 and the microprocessor 21 are entirely fixedwithin the housing 18 by means of the synthetic resin 22 (See FIG. 3).

The host computer 43 is a computer having a CPU, a memory, a hard disc,a CD-ROM drive and a floppy disc drive. A display 46 (display device), akeyboard 47 (input device) and a printer 47 (output device) areconnected to the host computer 43 via interface cables 44, 45.

In the card reading station 41, if the photo-sensor 12 detects themagnetic card 23 being inserted into the card reading station 41 throughthe card inlet 9, the photo-sensor 12 outputs card insertion signals tothe host computer 43. Upon receipt of the card insertion signals, thehost computer 43 commands the microprocessor 21 of the magnetic head 17to read the data stored on the card 23.

If the photo-sensors 13, 14 detect the magnetic card 23 passing by themagnetic head 17 and being ejected from the card outlet, thephoto-sensors 13, 14 respectively output card passage signals to thehost computer 43. In response to the card passage signals, the hostcomputer 43 commands the microprocessor 21 to stop reading the data.

This magnetic card reader 40 adopts MIX cryptosystem which is acombination of the public key cryptosystem (RSA cryptosystem) and acommon key cryptosystem (DES cryptosystem) to encrypt and decrypt thedata between the microprocessor 21 and the host computer 43.

The MIX cryptosystem is a encryption system making good use ofadvantages offered by the RSA cryptosystem and the DES cryptosystem,respectively. More specifically, a data processing rate based on the DESalgorithm is as fast as approximately {fraction (1/100)} of the dataprocessing rate based on the RSA algorithm, on the plus side, and it isdifficult for the DES cryptosystem to distribute keys in security andthe number of keys to be managed is large, on the minus hand. The RSAcryptosystem is not only advantageously free from delivery of theprivate keys but also the number of keys to be managed is far less thanthe number of keys to be managed by the DES cryptosystem. Thus the MIXcryptosystem uses the advantage of the DES cryptosystem makes good useof the high data processing rate provided by the DES cryptosystem and ofthe facile key management provided by the RSA cryptosystem. According tothe MIX cryptosystem, the microprocessor 21 decrypts the data on thebasis of a DES algorithm 58 and decrypts a common key 57 (DES key) usedto make up another DES algorithm 64 on the basis of a RSA algorithm 56.

Upon receipt of the card insertion signals from the photo-sensor 12 (SeeFIG. 2), the host computer 43 generates a public key 50 used for the RSAalgorithm and a private key 51 used to decrypt an encrypted common key57, as illustrated in FIG. 6. The private key 51 is input to a keymanagement utility 52 of the CPU and address-allocated by the keymanagement utility 52 in a predetermined manner. The private key 51 isinput from the key management utility 52 to a private key file 53 of thememory and stored therein. The public key 50 is input from the hostcomputer 43 to a key management utility 54 of the microprocessor 21 viathe interface cable 42 and address-allocated by the key managementutility 54. The public key 50 is input from the key management utility54 to a public key file 55 of the cache memory and stored therein.

Upon receipt of digital signals 59 from the A/D converter chip 20, themicroprocessor 21 takes the public key 50 out from the public key file55 and makes up the RSA algorithm 56 using the public key 50. Themicroprocessor 21 generates the common key 57 (DES key) used for the DESalgorithm 58 and then encrypts the common key 57 in accordance with theRSA algorithm 56. The microprocessor 21 makes up the DES algorithm 58using the common key 57 and encrypts digital signals 59 in accordancewith the DES algorithm 58. The common key 57 is input to a keymanagement utility 60 and address-allocated by the key managementutility 60 in a predetermined manner. The common key 57 is input fromthe key management utility 60 to a common key file 61 of the cachememory of the microprocessor 21 and stored therein. The microprocessor21 outputs the encrypted common key 57 together with the encrypteddigital signals 59 to the host computer 43 via the interface cable 42.

Upon receipt of the encrypted common key 57 and the encrypted digitalsignals 59 from the microprocessor 21, the host computer 43address-allocates the encrypted common key 57, then stores the commonkey 57 in a temporary file 62 of the memory, takes the private key 51out from the private key file 53 of the memory and makes up a RSAalgorithm 38 using this private key 51. The host computer 43 decryptsthe encrypted common key 57 in accordance with the RSA algorithm 63. Thehost computer 43 makes up a DES algorithm 64 using the decrypted commonkey 57. The host computer 43 decrypts the encrypted digital signals 59in accordance with the DES algorithm 64 and thereby obtains data 65stored on the magnetic card 23.

The private key 51 taken out from the private key file 53 corresponds tothe public key 50 having been used by the microprocessor 21 to encryptthe common key 57, on one hand, and corresponds to the common key 57having been used by the microprocessor 21 to encrypt the digital signals59.

The host computer 43 outputs the decrypted digital signals 59 in theform of character data to the display 46 and outputs the decrypteddigital signals 59 in the form of print data to the printer 47. The hostcomputer 43 stores the encrypted digital signals 59 as well as thedecrypted digital signals 59 in the memory.

With this magnetic card reader 40, any device adapted for illegalreading out of the data in the form of analog or digital signals can notbe attached thereto unless the magnetic head 17 is disassembled. In thecase of this magnetic card reader 40, even if the data stored on themagnetic card 23 is illegally read out, the data can not be immediatelyused since the data has been encrypted by the microprocessor 21 of themagnetic head 17.

The public key cryptosystem is not limited to the RSA cryptosystem andit is possible to adopt any one of EPOC cryptosystem, Rabincryptosystem, Diffie-Hellman ElGamal cryptosystem, and Elliptic CurveDiffie-Hellman Elliptic Curve ElGamal cryptosystem. It is also possibleto adopt the common key cryptosystem alone. In this case, the common keycryptosystem is not limited to the DES cryptosystem and it is possibleto any one of FEAL cryptosystem, IDEA cryptosystem, MISTY cryptosystem,MULTI cryptosystem and RC2/4/5 cryptosystem.

The magnetic head may include, in addition to a microprocessor, a gatearray, a field programmable gate array or a dedicated hard ware.

The card reading station is not limited to that of the electricmotor-driven insertion type but may be of the manual slide type. Theinterface cable may be selected from a group including a RS-232C cable,a RS-422A cable and a RS-423A cable.

The magnetic head according to this invention is applicable also to amagnetic ink character reader used to read a portfolio coated with amagnetic ink.

The magnetic head according to this invention is able to encrypt thedata read out from the magnetic storage medium so that, even if theencrypted data is illegally read out, the encrypted data can not be usedunless the encrypted data are decrypted. In this way, it is reliablyprevented to duplicate the magnetic storage medium.

With the embodiment of the magnetic head containing the core, the A/Dconverter chip and the microprocessor within the housing, it isimpossible to attach any device adapted for illegal reading out of thedata either before or after A/D conversion unless the magnetic headitself is disassembled. In view of this feature also, illegal readingout of the data is substantially impossible.

With the embodiment of the magnetic head having the A/D converter chipand the microprocessor fixed within the housing by means of syntheticresin, the magnetic head can be disassembled first after the syntheticresin has been removed. However, removal of the synthetic resininevitably results in destruction of the A/D converter chip and themicroprocessor. This feature further reliably prevent the intention toattach any device adapted for illegal reading out of the data to the A/Dconverter chip and the microprocessor.

What is claimed is:
 1. A magnetic card reader having a magnetic headadapted to read predetermined data from a magnetic card using a magneticmaterial to store said predetermined data, wherein: said magnetic headcomprises a core with a coil adapted to sense said data stored on saidmagnetic card reader as analog signals, and an A/D converter chipelectrically connected to said coil and adapted to convert said analogsignals to corresponding digital signals and an IC electricallyconnected to said A/D converter chip, said core, said A/D converter chipand said IC are contained in a housing defining an outer peripheralsurface of said magnetic head said A/D converter chip and said IC beingfixed within said housing by means of a synthetic resin filled in saidhousing, said magnetic reader including a node terminal electricallyconnected to said IC said IC and said node terminal encrypting saiddigital signals in accordance with a cryptosystem between said IC andsaid node terminal, and said node terminals decrypts said digitalsignals having been encrypted in accordance with said cryptosystem. 2.The magnetic head according to claim 1, wherein said IC is selected froma group including a microprocessor, a gate array, a field programmablegate array and a dedicated hard ware.
 3. The magnetic card readeraccording to claim 1, wherein said node terminal is capable of storingsaid digital signals having been encrypted and encrypted, respectively.